III-nitride crystal manufacturing method, III-nitride crystal substrate, and III-nitride semiconductor device

Abstract

Affords methods of manufacturing bulk III-nitride crystals whereby at least the surface dislocation density is low globally. The present III-nitride crystal manufacturing method includes: a step of preparing an undersubstrate ( 1 ) containing a III-nitride seed crystal, the III-nitride seed crystal having a matrix ( 1 s ), and inversion domains ( 1 t ) in which the polarity in the <0001> directions is inverted with respect to the matrix ( 1 s ); and a step of growing a III-nitride crystal ( 10 ) onto the matrix ( 1 s ) and inversion domains ( 1 t ) of the undersubstrate ( 1 ) by a liquid-phase technique; and is characterized in that a first region ( 10 s ), being where the growth rate of III-nitride crystal ( 10 ) growing onto the matrix ( 1 s ) is greater, covers second regions ( 10 t ), being where the growth rate of III-nitride crystal ( 10 ) growing onto the inversion domains ( 1 t ) is lesser.

1. A III-nitride crystal manufacturing method, including:
 a step of preparing an undersubstrate containing a III-nitride seed crystal, the III-nitride seed crystal having a matrix, and inversion domains in which the polarity in the <0001> directions is inverted with respect to the matrix; and 
 a step of growing a III-nitride crystal onto the matrix and inversion domains of the undersubstrate by a liquid-phase technique; characterized in that
 a first region, being where the growth rate of III-nitride crystal growing onto the matrix is greater, covers second regions, being where the growth rate of III-nitride crystal growing onto the inversion domains is lesser. 
 
 
     
     
       2. The III-nitride crystal manufacturing method set forth in  claim 1 , characterized in that in the undersubstrate, the surface of the inversion domains is recessed relative to the matrix surface. 
     
     
       3. The III-nitride crystal manufacturing method set forth in  claim 1  or  claim 2 , characterized in that along a {0001} plane on the undersubstrate, the inversion domains are in the form of a plurality of stripe regions, with the striped regions being arranged parallel to each other at regular intervals. 
     
     
       4. The III-nitride crystal manufacturing method set forth in  claim 1  or  claim 2 , characterized in that along a {0001} plane on the undersubstrate, the inversion domains are in the form of a plurality of dot regions, with the dotted regions being arranged two-dimensionally at regular intervals. 
     
     
       5. The III-nitride crystal manufacturing method set forth in  claim 1  or  claim 2 , characterized in that along a {0001} plane on the undersubstrate, the inversion domains are in a honeycomb form, arranged two-dimensionally in closed-packed regular hexagons. 
     
     
       6. The III-nitride crystal manufacturing method set forth in  claim 1  or  claim 2 , characterized in that the III-nitride crystal is grown to a thickness of 1 μm or more. 
     
     
       7. The III-nitride crystal manufacturing method set forth in  claim 1  or  claim 2 , characterized in that the resistivity of the III-nitride crystal is in its surface is 1×10 5  Ω·cm or more. 
     
     
       8. The III-nitride crystal manufacturing method set forth in  claim 1  or  claim 2 , characterized in that the III-nitride crystal is grown in a nitride reaction vessel. 
     
     
       9. The III-nitride crystal manufacturing method set forth in  claim 1  or  claim 2 , including a step of causing III-nitride crystal that has been grown onto the undersubstrate by a liquid-phase technique to grow further by a vapor-phase technique.